To clarify, I'm seeing this in Demo and Staging environments, but not yet in production. Servers appear to respond to configure, rebuild, restart, stop, and start, but no matter, when our application tries to query sphinx, we get this error.

I also tried removing the flying-sphinx add-on from our demo application (hoping that in re-adding it would spin up on a server without the issue) and now when I try to re-add heroku says "Could not communicate with vendor"

Still seeing these issues after your update. I was able to re-add sphinx to my Demo instance and configure, index, and start, but as soon as I try to load app pages I'm still seeing the lost connection error.

Good to know things are working again (certainly, my tests just
now indicated everything was fine). I'll be looking into the root
cause of the issue to find out exactly what's wrong, but at this
stage, I believe the database problem at the API caused problems
for the Sphinx proxy on each server (which expects authentication
for each app) and it couldn't pair your apps to the right daemons
because of that API 500 error.